This application is related to application Ser. No. 08/301,764 entitled "Energy Efficient Refrigerator Control System", which is assigned to the assignee of the present invention and is incorporated herein by reference.
This invention relates generally to refrigerators and in particular to damper systems for controlling the flow of air to different compartments within the refrigerator.
In most conventional refrigerators, a fan is used to produce air flow over the coils of an evaporator in order to cool the air. The cooled air then passes into a plenum in which the flow is typically split such that a portion of the air flow is directed into one or more freezer compartments and the other portion of the air flow is directed into fresh food compartments of the refrigerator. The split of air flow between the freezer and fresh food compartments is typically made by a damper that directs the majority of the air flow into the freezer compartment, which is necessary in order to maintain that compartment at a sub-freezing level.
In most conventional refrigerators the position of the damper is either fixed at time of manufacture or adjustable within a small range, either manually by the operator or by an automated control. The limits on the range of adjustment typically are such that the majority of air flow in all damper settings is still directed to the freezer compartment. A number of problems arise from the fixed damper or manually-variable damper in conventional refrigerators. For example, in refrigerators with manual control of damper position, the setting of the damper position is a trial and error process for the operator to attempt to achieve a desirable setting for the current operating conditions of the refrigerator (such as load in the respective compartments, ambient conditions around the refrigerator, etc.). Further, because the predominant cooling-air flow in both the fixed damper and manually-variable damper units is to the freezer, in some common operations, such as when the fresh food compartment door is open for a substantial amount of time for loading material into the compartment, the increased cooling load causes the refrigeration apparatus (compressor, evaporator and associated equipment) to operate, yet only a relatively small portion of the cooling-air flow is directed to the compartment in which the greatest cooling load exists. This type of operation wastes energy. Further, cooling air directed away from the freezer to the fresh food compartment has a very low humidity at fresh food compartment temperatures, causing dehydration of the stored food. In the conventional refrigerator, the defrost cycle of the freezer also requires much energy as it involves heating the evaporator or the air around the evaporator to remove the frost, after which it is necessary that the refrigeration apparatus operate to cool air for the refrigerator compartments
It is thus desirable to improve the energy efficiency and temperature control in a refrigerator by control of the cooling-air flow. Ideally the air flow is controlled so that the cooled air from the refrigeration apparatus is directed only into the compartment or regions in the refrigerator that need cooling. Such an air flow control system desirably is simple, with a minimum of moving parts, and is readily incorporated into the refrigerator in the fabrication process.
It is an object of this invention to provide a refrigerator having a cooling-air flow control device that improves the energy efficiency of the refrigerator and that provides directed cooling-air flow selectively to a compartment or compartments in which a cooling demand exists.
It is a further object of this invention to provide a high reliability cooling-air flow control device having few moving parts and that is readily incorporated into the refrigerator.